doc/SetClassProcs.3


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'\"
'\" Copyright (c) 2000 Ajuba Solutions.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: SetClassProcs.3,v 1.1 2000/11/22 01:50:26 ericm Exp $
'\" 
.so man.macros
.TH Tk_SetClassProcs 3 8.4 Tk "Tk Library Procedures"
.BS
.SH NAME
Tk_SetClassProcs \- register widget specific procedures
.SH SYNOPSIS
.nf
\fB#include <tk.h>\fR
.sp
\fBTk_SetClassProcs\fR(\fItkwin, procs, instanceData\fR)
.SH ARGUMENTS
.AS Tk_ClassProc instanceData
.AP Tk_Window tkwin in
Token for window to modify.
.AP Tk_ClassProcs *procs in
Pointer to data structure containing widget specific procedures.
The data structure pointed to by \fIprocs\fR must be static:
Tk keeps a reference to it as long as the window exists.
.AP ClientData instanceData in
Arbitrary one-word value to pass to widget callbacks.
.BE

.SH DESCRIPTION
.PP
\fBTk_SetClassProcs\fR is called to register a set of procedures that
are used as callbacks in different places.
.PP
The structure pointed to by \fIprocs\fR contains the following:
.CS
typedef struct Tk_ClassProcs {
	unsigned int \fIsize\fR;
	Tk_ClassWorldChangedProc *\fIworldChangedProc\fR;
	Tk_ClassCreateProc *\fIcreateProc\fR;
	Tk_ClassModalProc *\fImodalProc\fR;
} Tk_ClassProcs;
.CE
The \fIsize\fR field is used to simplify future expansion of the
structure. It should always be set to (literally) \fBsizeof(Tk_ClassProcs)\fR.
.PP
\fIworldChangedProc\fR is invoked when the system has altered
in some way that requires some reaction from the widget.  For example,
when a font alias (see the \fBfont\fR manual entry) is reconfigured,
widgets configured to use that font alias must update their display
accordingly.  \fIworldChangedProc\fR should have arguments and results
that match the type \fBTk_ClassWorldChangedProc\fR:
.CS
typedef void Tk_ClassWorldChangedProc(
	ClientData \fIinstanceData\fR);
.CE
The \fIinstanceData\fR parameter passed to the \fIworldChangedProc\fR
will be identical to the \fIinstanceData\fR paramter passed to
\fBTk_SetClassProcs\fR.
.PP
\fIcreateProc\fR is used to create platform-dependant windows.  It is
invoked by \fBTk_MakeWindowExist\fR.  \fIcreateProc\fR should have
arguments and results that match the type \fBTk_ClassCreateProc\fR:
.CS
typedef Window Tk_ClassCreateProc(
	Tk_Window \fItkwin\fR,
	Window \fIparent\fR,
	ClientData \fIinstanceData\fR);
.CE
The \fItkwin\fR and \fIinstanceData\fR parameters will be identical to
the \fItkwin\fR and \fIinstanceData\fR parameters passed to
\fBTk_SetClassProcs\fR.  The \fIparent\fR parameter will be the parent
of the window to be created.  The \fIcreateProc\fR should return the
created window.
.PP
\fImodalProc\fR is invoked after all bindings on a widget have been
triggered in order to handle a modal loop.  \fImodalProc\fR should
have arguments and results that match the type \fBTk_ClassModalProc\fR:
.CS
typedef void Tk_ClassModalProc(
	Tk_Window \fItkwin\fR,
	XEvent *\fIeventPtr\fR);
.CE
The \fItkwin\fR parameter to \fImodalProc\fR will be identical to the
\fItkwin\fR parameter passed to \fBTk_SetClassProcs\fR.  The
\fIeventPtr\fR parameter will be a pointer to an XEvent structure
describing the event being processed.

.SH KEYWORDS
callback, class